//通过js设置css样式
let btn = document.querySelector('.btn')
btn.onclike = function () {
    //给图片设置边框，设置padding，设置圆角
    let pic = document.querySelector('.pic')
    pic.style.border = '1px solid #ddd'
    pic.style.widtn = '200px'
    pic.style.padding = '5px'
    pic.style.borderRadious = '5px'
}